Cross-medium rigid-flexible coupled modeling and trim analysis of helicopter mine-clearing system

Naval mines present a severe threat to maritime safety. Helicopter-based mine clearing, compared to traditional ship-based methods, offers faster deployment, higher efficiency, and lower risk. However, there is still a lack of publicly available modeling theories and analytical methods applicable to such systems. This paper establishes a cross-medium large-flexible towing cable model based on the absolute node coordinate formulation. Additionally, a rigid-body dynamics model for the helicopter and towing body, which facilitates easy coupling integration, is developed. The cross-medium rigid-flexible coupling model for the helicopter mine-clearing system is constructed and validated. A partitioned trim method for the coupled system is proposed, and the effects of key design and flight parameters on trim characteristics are analyzed. Results show that as flight speed increases, the helicopter nose-down attitude intensifies, while placing the towing point behind and above the center of gravity improves the attitude. During turns, the towing cable tension suppresses helicopter roll motion, requiring additional lateral control to provide centripetal force for turning. Lower flight altitude and longer cables are ineffective at significantly increasing the depth of the towing body, necessitating the installation of sinking components on the towing body.